1. Field of the Invention
The present invention relates generally to a heat exchanger for an automotive vehicle. More particularly, the present invention relates to an automotive heat exchanger core having a side support which prevents fin damage during the assembly operation.
2. Disclosure Information
Typical automotive heat exchangers, such as radiators, include a plurality of thin-walled tubes interleaved with corrugated fins enclosed in a core frame. The fins are rigidly attached to the tubes as well as to a pair of frame side supports while the tubes are joined to a pair of headers. The frame side supports are attached also to the headers. As is well known in the art, coolant passes from one header through the tubing to the other header. As the temperature of the coolant passing through the heat exchanger core increases, the core expands.
Heat exchanger cores are manufactured by assembling the plurality of tubes interleaved with fins between the pair of side support members. The core is precompressed by a variety of known methods prior to brazing to maintain the tube and fins in proper relationship. One known method is to precompress the core with one or more steel bands completely surrounding the core before brazing. After banding, the core is inserted into a furnace and heated until it brazes together. After brazing, the steel bands are cut from the core and discarded or reused. In addition, these bands often distort and/or skew the core which can result in leaks and/or improper vehicle fit.
Other types of brazing fixtures have been proposed such as that shown in U.S. Pat. No. 5,165,163, assigned to the assignee of the present invention. The brazing fixture includes a plurality of brazing stations each having a pivotal lever which applies a compressive force against one of the side support members of the heat exchanger while the other side support member is held stationary in the fixture. However, these fixtures tend to become corroded in the brazing atmosphere, reducing the effectiveness of the compressive force applied against the core. Also, these fixtures usually are not used upstream of the braze process due to sheer weight and mass. Heating these fixtures in a braze furnace requires much energy due to their large mass. This adds expense and delay to the manufacturing process.
A third type of brazing fixturing is proposed in U.S. Pat. No. 3,894,580. In this fixture, a pair of generally parallel ties extend between each of the side support members to fix the core in a predetermined position prior to the brazing operation. The disadvantages of using the generally parallel ties is that unless an elaborate and complicated clamping mechanism, such as shown in U.S. Pat. No. 3,894,580 is utilized on each end of the ties, the heat exchanger core can still skew as a result of normal process handling and/or shrinkage and thermal cycling during the brazing operation. This skewing or misalignment of the heat exchanger core often results in deleterious effects upon the core such as leaking and/or improper vehicle fit.
U.S. Pat. No. 5,450,997, also assigned to the assignee of the present invention, overcomes the problems associated with some prior art brazing fixtures by providing a pair of rod members which engage the side support members of the heat exchanger. The rod members are diagonally placed into holes in the side support members of the heat exchanger, such as a radiator, to prevent skewing. This is shown in FIGS. 1A and B. As shown, the rod members 10 engage the side support members 12 to provide a compressive force to the core 14. A fin member 16 is always placed adjacent the side support members 12. Because of manufacturing variations, the rod members may be slight too short or too long when placed in the side supports 12. As illustrated in FIG. 1B, if the rod members 10 are too short, damage to the fin members 16, such as crushing, is possible because the fin members are manufactured from very light gage material. The heat exchanger core must then be scrapped, resulting in waste of material, time and labor.
It would, therefore, be advantageous to provide an effective method for preventing fin damage in a heat exchanger core during a manufacturing process.